(1) Field of the Invention
The present invention relates to an apparatus for and process of charging a shaft furnace of the type used in the manufacture of steel. More particularly, the present invention relates to an apparatus for and process of introducing and distributing charge to a desired area within a shaft furnace.
(2) Description of the Prior Art
The construction of modern high production blast furnaces imposes new and more stringent demands on the apparatus for charging the blast furnace due to increased internal pressures within the furnace and increased surface dimensions of the burden over which the charge must be distributed.
Conventional charging devices such as those employing charging bells and compensating chambers exhibit a number of serious disadvantages. With the use of charging bells and compensating chambers, optimum distribution of the furnace charge over the charging area was either difficult or possible. In the prior art, it was determined that it was desirable to control the distribution of the charge within the furnace.
U.S. Pat. No. 3,693,812 describes a device which provides for distribution of a furnace charge in the desired areas inside the furnace. This patent discloses a charging apparatus wherein a chute is rotated about the vertical axis of the furnace, the angular position of the chute in relation to the axis of the furnace being adjustable. In the device described in this patent, one mechanical means rotates the chute and another mechanical means adjusts the angular position of the chute in relation to the axis. U.S. Pat. No. 3,880,302 discloses a mechanism for rotating the chute and for adjusting the angular position of the chute. In the improved mechanism disclosed in this patent, the movement of the chute is provided by two separate motors, by the use of wheels, by differential gears and by planetary gears. These driving mechanism enable the chute to be directed toward any desired point on the surface of the burden so that the charge may be deposited in patterns allowing for optimum operation of the furnace. However, these driving mechanisms are complex and expensive to manufacture.
The rotary-chute charging devices described above are particularly suited for distribution of charge in a shaft furnace having a circular cross section. This is particularly the case in that it is the general practice to distribute the charge in concentric circles. Alternatively, the charge may be distributed in a spiral configuration. However, it has been found that the rotary-chute charging devices of the prior art are unsatisfactory for use in furnaces having irregularly shaped cross sections, that is, noncircular cross sections such as polygons including rectangular or square cross sections. In order to use a rotary-chute charging device in a polygonal shaped blast furnace, it is necessary to use extremely complex regulating programs.
In addition to the above-described rotary-chute charging devices, other devices have been proposed which allow for control of the direction of a chute within a blast furnace in order to distribute charges in a desired manner. German Patent Application No. 2,104,116 discloses a chute mounted by means of a cardanic suspension so that the chute can be directed toward any point without having to rotate the chute suspension system. However, the mechanisms for mounting, securing and driving the chute are extremely complex so that the device is not, in general, desirable to use in connection with blast furnaces. Moreover, this patent application does not disclose a process for charging a furnace having a rectangular cross section.
A particular problem is prevalent with blast furnaces having a rectangular cross section. As the charge flow downwardly through the chute, the charge travels in a linear pattern. However, once the charge is ejected from the chute, the charge free-falls in a parobolic pattern into the furnace. When it is desired to introduce charge into the corners of a furnace having a rectangular cross section, the direction of the chute must be adjusted upwardly to enable the accurate placement of the charge in the corners. In the aforementioned patents and patent applications, this problem was not confronted in that the furnaces described were of a circular cross section. As disclosed in these patents and patent applications, the chutes could be angled in order to fill areas of the burden near the walls of the cylindrically shaped blast furnace.
It is one object of the present invention to provide a shaft furnace charging apparatus which will distribute charge within furnaces having either a circular cross section or those with an irregular cross section.
Another object of the present invention is to provide a furnace charging apparatus that has a simple structure and that is relatively inexpensive to construct.
It is a further object of the invention to provide a shaft furnace charging apparatus which is readily accessible and separable into its various parts to provide for maintenance thereof.
It is another object of the invention to provide a process for introducing and distributing a charge in a shaft furnace in a way so as to insure that the charge will be distributed in an optimal manner regardless of the shape of the cross section of the furnace.